U.S. patent number 7,063,713 [Application Number 09/890,715] was granted by the patent office on 2006-06-20 for method for severing or removing a biological structure, especially bones.
This patent grant is currently assigned to Wittenstein GmbH & Co. KG. Invention is credited to Rainer Baumgart, Michael Butsch.
United States Patent |
7,063,713 |
Butsch , et al. |
June 20, 2006 |
Method for severing or removing a biological structure, especially
bones
Abstract
The invention relates to a method for severing or removing a
biological structure, especially bones, by using a water jet
cutting device (R) from which a pressurized severing medium (4) is
discharged. According to the invention, the severing medium (4)
should be projected onto the biological structure in a pulsed
manner.
Inventors: |
Butsch; Michael (Daisendorf,
DE), Baumgart; Rainer (Munich, DE) |
Assignee: |
Wittenstein GmbH & Co. KG
(Igersheim, DE)
|
Family
ID: |
7896505 |
Appl.
No.: |
09/890,715 |
Filed: |
December 28, 1999 |
PCT
Filed: |
December 28, 1999 |
PCT No.: |
PCT/EP99/10399 |
371(c)(1),(2),(4) Date: |
December 31, 2001 |
PCT
Pub. No.: |
WO00/45719 |
PCT
Pub. Date: |
August 10, 2000 |
Foreign Application Priority Data
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|
|
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Feb 5, 1999 [DE] |
|
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199 04 640 |
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Current U.S.
Class: |
606/167;
604/22 |
Current CPC
Class: |
A61B
17/3203 (20130101) |
Current International
Class: |
A61B
17/32 (20060101) |
Field of
Search: |
;606/166,167 ;604/22
;451/39,40,102,222 ;83/53,177 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Robert; Eduardo C.
Assistant Examiner: Davis; D. Jacob
Attorney, Agent or Firm: Bachman & LaPointe, P.C.
Claims
The invention claimed is:
1. A cutting-nozzle element for severing or removing a biological
structure when the cutting-nozzle element is fed with a fluid under
pressure, comprising a hollow cutting-nozzle body having a
longitudinal axis, the hollow cutting-nozzle body receives a
shut-off element which is movable within the hollow cutting-nozzle
body in a reciprocating manner along the longitudinal axis wherein
the hollow cutting-nozzle body defines with the shut-off element an
annular space, at least one nozzle extending radially with respect
to the longitudinal axis and communicating with the annular space,
and further including means for reciprocating the shut-off element
to provide a pulsed feed of fluid under pressure to the at least
one radial nozzle.
2. An element according to claim 1, wherein the means for
reciprocating comprises (1) a biasing means for moving the shut-off
element in a first direction and (2) means for selectively moving
the shut-off element in a second direction opposite the first
direction for feeding fluid under pressure in a pulsed manner to
the annular space.
3. An element according to claim 2, wherein the means for
selectively feeding comprises a variable gap formed between a
surface of the shut off element and an inner wall of the
cutting-nozzle body.
4. An element according to claim 3, wherein the means for
selectively moving the shut-off element in the second direction
comprises a motor means which receives fluid under pressure via the
variable gap.
5. An element according to claim 4, wherein the fluid motor means
comprises a shoulder on the shut-off element which has a first
surface which is acted on by the fluid under pressure.
6. An element according to claim 5, wherein the shoulder has a
second surface which is acted on by the biasing means in opposition
to the first surface.
7. An element according to claim 1, wherein the shut-off element
has an internal passage for removing the fluid and biological
structure.
Description
BACKGROUND OF THE INVENTION
The invention relates to a method of severing or removing a
biological structure, in particular bone, having a water-jet
cutting system from which a severing medium under high pressure is
discharged, and to a cutting-nozzle element and a water-jet cutting
system.
Such methods are known on the market and are in use in many
different forms and designs. In particular in medicine, it is known
to sever, for example from outside, a bone by water-jet cutting. A
disadvantage with this is that, in conventional water-jet cutting
methods, the soft tissue, and not only the bone, is destroyed. The
vascular system in the soft tissue at the bone is important in
particular for the knitting of the bone or for the regeneration of
the callus. It is therefore necessary during the water-jet removal
or severing of biological substances, in particular of bones, to
carry out the removal or severing of the bone as carefully as
possible. In conventional water-jet cutting methods, the water is
applied directly to the exposed bone via a cutting nozzle, in the
course of which the vascular system in the bone is also
damaged.
An arrangement for cutting by means of a liquid jet has been
disclosed by EP 0 636 345 A1, in which arrangement an additional
medium is added to a liquid jet by means of vacuum. In this case,
pulsing of a liquid jet is produced in a handle, the liquid jet
being discharged under pressure losses via an elongated cannula
adjoining the handle.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method and a
water-jet cutting system having a cutting-nozzle element with which
removal and/or severing of biological substances, in particular of
bones, is possible in a simple and careful manner. The ease of
manipulation of corresponding water-jet cutting systems having
cutting-nozzle element with which removal and/or severing of
biological substances, in particular of bones, is possible in a
simple and careful manner. The ease of manipulation of
corresponding water-jet cutting systems having cutting-nozzle
elements is also to be considerably improved. Furthermore, it is
the object of the present invention to shorten the operation times,
in particular during the severing of bones, in which case high
operation costs are to be reduced as a result. In addition, an
operation is to carried out with substantially greater care and
with a quicker recovery for the patient.
This object is achieved by the severing medium being discharged
onto the biological structure in a pulsed manner.
This ensures that, in particular, the soft tissue is moved back by
a pulsed jet and then the severing medium strikes the bone in order
to partly remove the bone or to sever it. In this case, it may be
advantageous to insert a corresponding cutting nozzle for severing
the bone into the marrow cavity of the bone and to provide the bone
radially with a notch from inside. For example, a radially arranged
nozzle in a cutting-nozzle element is rotated in the marrow cavity
of a tubular bone during the discharge of the severing medium. In
the process, the bone can be severed at least partly from inside.
It may possibly also be sufficient to cut only one notch in the
bone, so that it can subsequently be severed or pierced in a
conventional manner from outside by a small blow. The outer
periosteum is not destroyed in the process. Subsequent further
treatment of the bone, for example traction, may then be carried
out.
However, it is important that a pulsed water jet is discharged from
a nozzle opening of a cutting-nozzle body in a quite specific
manner via this method, i.e. at a quite specific frequency and with
a pressure change. This pulsation or pulsing is defined as a
pressure change of a water jet which undergoes either only a slight
pressure change or a complete pressure change up to the absolute
pressure drop. A biologically suitable inorganic and/or organic
abrasive agent can be fed to the severing medium so that the
material-removal capacity is considerably increased during the
water-jet cutting. In this way, bones can be severed with
substantially lower pressures.
However, it is important that the pulsed discharge of the severing
medium results in soft, elastic tissue being moved back upon
impingement of the severing medium, whereas the bone tissue is
severed or removed when the severing medium impinges on said bone
tissue.
Owing to the fact that the severing medium is discharged onto the
biological structure in a pulsed manner, and working pressures
which would lead to destruction of the softer structures without
pulsation are used, and these soft biological structures, on
account of their higher elasticity compared with the surrounding
harder biological structures, are subjected to lower mechanical
loading within the elastic range through suitable selection of the
pulsation, the harder biological structures are severed due to the
fact that the elasticity or fracture limit is exceeded.
If a cutting-nozzle element is inserted into the bone, a
corresponding element, in particular a tube element or the like, is
provided in order to draw the discharging medium out of the
interior of the bone.
The pulsation is produced in the cutting nozzle essentially by
varying cross sections in the cutting-nozzle element itself. This
has the advantage that no inertia losses, for example due to long,
possibly elastic or resilient, tube lines, would weaken a changing
pressure impulse.
So that a corresponding pulsation can be produced in the individual
cutting-nozzle elements, a shut-off element sits inside a
cutting-nozzle body, this shut-off element influencing a medium,
flowing along inside or outside the latter, by a rotational or
translatory reciprocating movement. A change of cross section is
effected in the process, a pressure change, in particular a
pressure drop, is effected. The pressure drop may even approach
zero.
However, within the scope of the present invention, it is also
intended that the pressure changes can take place within small and
also large ranges. There are no limits to the invention in this
respect either.
In the preferred exemplary embodiment, a cutting-nozzle element
which has at least one radial cutting-nozzle opening is formed.
This cutting-nozzle element is inserted into a bone, if necessary
held in a certain position via end spacers (not shown). By axial
rotation of the cutting-nozzle body, with simultaneous discharge, a
notch is produced in the bone, or the bone is even severed. So that
the outflowing severing medium does not remain in the bone interior
space, the corresponding shut-off element, which is provided inside
the cutting-nozzle body, is designed as a hollow shaft and can draw
the liquid out of the interior space of the bone. So that other
uses for severing or removing bones are also possible,
cutting-nozzle elements which have end nozzle openings are shown in
other exemplary embodiments. These nozzle openings can also be
opened and closed at a certain frequency, which is selectable, so
that a pulsed water jet can be discharged.
A corresponding water-jet cutting system is equipped with an
interchangeable supply reservoir of varying size, in which case the
supply reservoir can essentially be connected to a
pressure-generating device in an interchangeable manner. The
pressure-generating device is preferably of electromechanical type
and moves a linear drive onto a plunger element. As a result, a
pressure which can be supplied to the cutting-nozzle element via a
connecting line is generated in a pressure space. The supply
reservoirs are preferably of a size which can be selected so as to
vary and contain the severing medium with, if necessary, abrasive
agents.
Only the cutting-nozzle element has to be cleaned after the
operation. The supply reservoir is merely exchanged and can be
recycled after use.
Furthermore, it is advantageous that such a water-jet cutting
system is exceptionally small and can be produced cost-effectively,
since any desired supply reservoir can be mounted on the
pressure-generating device.
BRIEF DESCRIPTION OF THE DRAWINGS
Further advantages, features and details of the invention follow
from the description below of preferred exemplary embodiments and
with reference to the drawing, in which:
FIG. 1 shows a schematic plan view of a water-jet cutting system
according to the invention with interchangeable supply
reservoir;
FIG. 2 shows a schematic partial longitudinal section through a
cutting-nozzle element according to the invention;
FIG. 3 shows a partial longitudinal section through a further
exemplary embodiment of a further cutting-nozzle element;
FIG. 4 shows a schematic partial longitudinal section through a
further exemplary embodiment of the cutting-nozzle element.
DETAILED DESCRIPTION
According to FIG. 1, a water-jet cutting system R according to the
invention for severing or removing a biological structure, in
particular a human bone, has a pressure-generating device 1,
adjoining which, preferably in an interchangeable manner, is a
supply reservoir 2. The supply reservoir 2 has a pressure space 3
in which a severing medium 4 is introduced. The severing medium 4
is preferably sterile and aseptic water, which, if necessary, is
enriched with abrasive agent 5. The abrasive agents 5 used may be
inorganic or organic substances, such as, for example, sodium
chloride, biological amino acids, monosaccharides and disaccharides
and also sugars and alcohols. These abrasive agents 5 may also be
supplied via injectors or the like (not shown here).
The supply reservoir 2 is closed by means of a plunger element 6,
which can be actuated via a linear drive 7 of the
pressure-generating device 1. The linear drive 7 is preferably an
extendable mechanical spindle which can be driven in particular as
an electromechanically operated linear actuator of the
pressure-generating device 1. Via gearing and things such as drive
elements (not shown here), the spindle can be extended and can
exert a very high pressure on the plunger 6. In this case, the
supply reservoir 2 is supported on the pressure-generating device 1
via a quick-acting lock 8. The quick-acting lock 8 may be of the
most varied type and have a threaded connection, a push-in
connection, a bayonet lock or the like. There are no limits to the
invention in this respect.
However, it is important that, after the severing medium 4 has been
completely discharged from the pressure space 3 by moving the
plunger element 6 in the direction of an outlet valve 9, the medium
4 is fed completely to the cutting-nozzle element S via a
connecting line 10. The severing medium 4 is discharged there
radially or axially under very high pressure.
The outlet valve 9 is preferably designed as a check valve. This
check valve is connected to the connecting line 10 such that it can
be released again, in which case consideration may also be given to
producing a releasable connection between outlet valve 9 and
pressure-generating device 1.
The functioning of the present water-jet cutting system is as
follows:
For the water-jet cutting, a severing medium under pressure, in
particular in a pressurized manner is fed to the cutting-nozzle
element S. To this end, the supply reservoir 2 is mounted on the
pressure-generating device 1. The severing medium 4 is poured in.
The supply reservoir 2 is then pressurized by being acted upon by
the plunger 6 via the linear drive 7, so that the severing medium 4
can be fed completely to the cutting-nozzle element S via the
connecting line 10. So that there is no idle time during the
operation, when a supply reservoir is empty for example, a second
pressure-generating device 1 having a second supply reservoir 2 may
be provided, this second pressure-generating device 1 jointly
feeding the severing medium 4 to the cutting-nozzle element S via a
directional control valve 11. While the one supply reservoir is
being emptied during the operation, the other supply reservoir can
be exchanged.
From the present inventive idea, different supply reservoirs 2
which have capacities of different size for severing agents and
which fit, for example, onto a single pressure-generating device 1
are also to be designed.
Shown in FIG. 2 is a possible cutting-nozzle element S.sub.1 which
has a cutting-nozzle body 12 which is designed to be hollow in the
interior. In the preferred exemplary embodiment, at least one
nozzle opening 13 is provided radially, through which the severing
medium 4 flows out under very high pressure for the severing,
cutting or removal.
Provided inside the cutting-nozzle body 13 is a shut-off element 14
which is axially movable in a reciprocating manner, as shown in
double arrow direction Y.
The shut-off element 14 forms a cone-like annular gap 16 via a cone
15 of the cutting-nozzle body 12, this cone 15 having a
corresponding profile of the same kind.
Following the cone 15, the shut-off element 14 is of constricted
design and forms an annular space 17 relative to the cutting-nozzle
body 14, the severing medium 4 flowing outward out of this annular
space 17 through the radial nozzle openings 13. A shaft shoulder 18
of the shut-off element 14 adjoins the annular space 17 and is
connected to the cutting-nozzle body 12 on the inside virtually
free of play. Adjoining the shaft shoulder 18, which also serves to
center and axially guide the shut-off element 14, is an
energy-storing element 19, which is supported at the end face on
the shaft shoulder 18 and is supported on the other side at the end
face on the cutting-nozzle body 12 on the inside. As a result, the
shut-off element 14 is permanently deflected in an X-direction. The
severing medium 4 flows through the annular gap 16 and is then
discharged from the nozzle openings 13 under high pressure via the
annular space 17.
However, it is important in the case of the present invention that
a pulsating jet is produced from the nozzle openings 13 on account
of a very small annular gap 16 in the region of the cone 15, the
severing medium being greatly accelerated in this annular gap 16.
This produces a vacuum which further reduces the annular gap 16
until severing medium 4 no longer flows. As a result, the shut-off
element 14 is moved against the X-direction shown. The
energy-storing element 19 is thereby loaded and applies pressure to
the shut-off element 14. The latter yields to the pressure of the
energy-storing element 19 and causes the shut-off element 14 to
move in the X-direction shown, so that the severing medium 4 can
again flow out through the widened annular gap 16, the adjoining
annular space 17 and thus through the nozzle opening 13. This
action repeats itself.
A pulsation can be controlled or set on the basis of pressures
which can be set in a varying manner and on the basis of selectable
energy-storing elements 19 and different geometries of the annular
gap 16. This pulsation serves essentially to sever bones and tissue
parts. It has proved to be especially favorable to use the
pulsation. Tissue structures which must not be damaged, such as the
periosteum for example, are moved only within the elastic range by
a pulsating jet. The pulsed jet then removes or severs the
biological structure, in particular the bone. This ensures that
periosteum or other soft tissue is attacked or damaged only
slightly during the severing of bone.
A tube element 22, which is preferably of elastic type, adjoins the
shut-off element 14. It permits an axial movement of the shut-off
element 14 in the Y-direction shown. At the same time, it serves to
draw off severing medium 4 which is located in the bone interior
when the cutting-nozzle element S.sub.1 is inserted into a bone
interior space.
Shown in a further exemplary embodiment of the present invention
according to FIG. 3 is a cutting-nozzle element S.sub.2 in which
the nozzle opening 13 is provided axially at the end face in the
cutting-nozzle body 12. A shut-off element 14 is inserted as hollow
shaft inside the cutting-nozzle body 12 of hollow design and is
rotatable about an axis 20 in the Z-direction shown. A discharge
opening 21 is provided at the end face in the shut-off element 14
of hollow design, which fits precisely into the cutting-nozzle body
12, the discharge opening 21 coinciding with the nozzle opening 13
in a certain position. However, the provision of a multiplicity of
discharge openings 21 at the end face is also intended to be within
the scope of the present invention, so that, when the shut-off
element 14 is rotated, the severing medium 4, which is introduced
inside the shut-off element 14 under high pressure, discharges
outward in a pulsating manner via the discharge opening 21 and when
the latter coincides with the nozzle opening 13. The pulsation or
the cyclical discharge of severing medium 4 from the nozzle opening
13 can be influenced by the number of corresponding discharge
openings 21 or by the rotational speed of the shut-off element 14
about an axis 20. The rotation may be effected in any desired
manner, mechanically, electromechanically or some other way.
Shown in the last exemplary embodiment of the present invention
according to FIG. 4 is a cutting-nozzle element S.sub.3 in which
the cutting-nozzle body 12 is designed to be hollow and has a
nozzle opening 13 at the end face in the region of an axis 20.
The shut-off element 14 sits in an axially movable manner inside
the cutting-nozzle body 12 and is of conical design and engages in
a correspondingly formed cone of the cutting-nozzle body 12. The
severing medium 4 flows between shut-off element 14 and the
interior space of the cutting-nozzle body 12 when the annular gap
16 is open. The annular gap 16 is opened and closed by a
translatory axial movement of the shut-off element 14 in double
arrow direction Y shown. This movement may be produced, for
example, mechanically, electromechanically or even by a
piezoelectric element. Many different possibilities which are
intended to fall within the scope of the invention are conceivable
here.
* * * * *